The invention is directed to a process for the production of furnace black by spraying oily carbon black forming material into a stream of hot combustion gases produced by the reaction of fuel with reaction air, chilling and recovery of the carbon black by separation from the waste gases during which the reaction air is preheated by means of the waste gases.
The furnace black process is a known process for the production of carbon black. For example it is described in Ullmanns Enzyklopadie der technischen Chemie, Vol. 14 page 800 (1963).
In a furnace black process carbon black is produced from a carbon black forming oil while hot combustion gases are produced by means of reaction air and a fuel, and the carbon black forming oil is atomized in these hot combustion gases. There is formed a carbon black-waste gas-aerosol which is cooled down. Subsequently the carbon black formed is separated from the waste gas, e.g. by means of a filter plant and the waste gas, in a given case, flared.
It is now known to conduct the waste gas over a heat exchanger and thus to preheat the reaction air and to return it again to the process for production of the carbon black (compare, e.g. Eideneiner German Pat. No. 2,131,903).
The process according to the state of the art, however exhibits various inadequacies and disadvantages.
Since the temperature of 720.degree.-750.degree. C. cannot be exceeded in carbon black containing waste gases in order that the carbon black quality is not influenced in a negative manner, the degree of preheating the reaction air is limited.
In uncertain weather conditions the preheating temperature also varies and therewith the carbon black quality because carbon black reactors and heat exchanger customarily are installed in the open air.
The carbon black containing waste gases flowing through the tubes or spirals cause a deposit of carbon black coatings on the surface of contact of the heat exchanger. The deposits in the production of low structured blacks and blacks with a certain content of residual oil are particularly thick. An insulation occurs through the deposits on the metallic surface so that the heat transfer is very poor and only a small heating of the reaction air takes place.
Because of these disadvantages in the furnace black process the temperature of the preheated air can only reach a temperature of 400.degree.-560.degree. C.